1. Field of the Invention
The present invention relates, in general, to air conditioners and, more particularly, to an air conditioner and a method of controlling the air conditioner, which allow a compressor to be smoothly started.
2. Description of the Related Art
Generally, a compressor functions to compress a low-pressure refrigerant which flows into an inlet side of the compressor using an eccentric unit mounted to a rotating shaft. A high-pressure refrigerant which is compressed by the eccentric unit is discharged to an outlet side of the compressor.
When it is required to temporarily stop and then re-start the compressor-due to various factors, the compressor is not smoothly re-started due to a difference in pressure between the inlet side and the outlet side of the compressor.
To smoothly re-start the compressor, according to related art, an electric expansion valve between an outdoor unit and an indoor unit is opened for a period of time to equalize a pressure of the inlet side with a pressure of the outlet side prior to re-starting the compressor.
However, when there is a small pressure difference between the inlet side and the outlet side of the compressor despite opening the electric expansion valve for the period of time, the compressor fails to re-start.
Further, when the compressor is not re-started for lengthy periods, a motor of the compressor is overloaded, thus resulting in damage to the compressor.
The above-mentioned problem is more frequently found in a variable capacity rotary compressor which is frequently stopped to vary compression capacity.
In Korean Patent Application No. 2002-61462 there is disclosed a variable capacity rotary compressor. In that application, the compressor was designed to execute a compression operation in either of two compression chambers having different interior capacities.
The variable capacity rotary compressor is designed to execute the compression operation in either of the two compression chambers while executing an idle operation in a remaining one of the two compression chambers by an eccentric unit, thus easily varying the compression capacity as desired by changing a rotating direction of a rotating shaft.
In an air conditioner having the variable capacity rotary compressor, when a required capacity of an indoor unit is changed, the motor of the compressor is temporarily stopped to vary a discharging amount of the refrigerant according to the required capacity of the indoor unit. Subsequently, after an elapse of a pressure equalizing period, the motor of the compressor is rotated in a direction opposite to an original rotating direction to execute a compression operation in a compression chamber where an idle rotation of the eccentric unit has been executed, thus re-starting the variable capacity rotary compressor.
However, in the conventional air conditioner, a refrigerant is slightly compressed by the rotation of the motor of the compressor even in the compression chamber where the idle rotation of the eccentric unit is executed. Thus, when the motor of the compressor is rotated to execute the compression operation in the compression chamber where the idle rotation of the eccentric unit has been executed, the rotation of the motor of the compressor may be restrained due to imbalance of pressure in the compression chamber. Thereby, the compressor may fail to re-start, thus lowering the probability of a successful re-starting. Further, in the conventional air conditioner, when the compression operation is executed in a compression chamber having a large capacity, the motor of the compressor is driven using a main winding of the motor, which has a relatively large mobile power. On the other hand, when the compression operation is executed in a compression chamber having a small capacity, the motor of the compressor is driven using a subsidiary winding of the motor, which has a relatively small mobile power. Thus, in the case of starting the compressor to execute the compression operation in the compression chamber having the small capacity, the mobile power is relatively low. Thereby, there is a higher probability that the compressor will fail to start.
Further, when a frictional resistance between an inner surface of a compression chamber and a roller which is in contact with the inner surface of the compression chamber is temporarily increased due to a mechanical allowance, the compressor may fail to start, resulting in a reduction of start reliability.